Locking only certain cells on worksheet

I have a workbok where I added 3 comboboxes that are positioned over 3 merged cells that are C6, C7, & C8. The comboboxes populate C6-C8 and C9 is just entered normally. I have a button on another page that toggles the visibility of the three comboboxes and locks the range C3:C9. It is working but I'm not getting it to unlock the range if the button is pressed again. code I'm using. I still want to be able to edit the rest of the sheet which seems to be working just not my range after the second button push.

Sheets("Sheet1").Activate
    ActiveSheet.Range(Cells(6, 3), Cells(9, 3)).Select
    If Selection.Locked = False Then
     Selection.Locked = True
    ElseIf Selection.Locked = True Then
     Selection.Locked = False
     End If

I get the error "Unable to set the Locked Property of the Range Class." on the second button push and Debug highlights the "Selection.Locked = False" after the ElseIf.

Can anyone point me to something to read or suggest something to address this?

Thanks for any help,

Mum-O-Killowe